A laminator comprises first and second rollers 2, 4 mounted in parallel for counter-rotation. One of the rollers 2 is supported on a pair of pneumatic cylinders 12, which can be operated to adjust the gap 6 between the rollers. When a desired gap 6 is reached for the thickness of workpiece to be laminated, locks 24 are operated to prevent further movement of the first roller 2 towards the second roller 4. Preferably the locks do not prevent movement of the first roller 2 away from the second roller 4. After the locks 24 have been engaged to protect the workpiece against crushing, the pressure applied to the first roller 2 during the laminating process can be changed.